Channel Morphologic Changes Associated with Invasive Vegetation Removal
Celeste Wieting1, Sara Rathburn2, Lindsay Reynolds3, Jonathan Friedman4, Derek Schook5
Canyon de Chelly, AZ, Nov. 2019
10050Meters
1,2Colorado State University3Bureau of Land Management
4United States Geological Survey5Water Resources Division, NPS
A Removal Database
As part of my research, I intend to compile site-specific data on vegetation removal projects.
Please email me if you would like to contribute to the database:
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Outline
How will the river respond?
• Post-removal monitoring usually overlooked
Invasive vegetation control methods
My research
i) A literature review of post-removal channel morphologic changes
ii) Ongoing reach- to segment-scale field monitoring – CACH
iii) Geomorphic-vegetation interactions through sediment dynamics – BIBE (In development)
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Rio Puerco, photo: J. Friedman
Cadol et al., 2011 (River Res. Applic.)
Scott et al., 2017 (Ecohydrology)
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A shift in the
geomorphic nature.
Erosion
Introduce Vegetation
Increased bank
stability
Channel Narrowing
Remove Vegetation
τo > τ c
↓ τo↑ τo
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Potential Response to Invasive Vegetation
Morphologic changesChannel narrowing
• Graf, 1978 (GSA Bulletin)
• Friedman et al., 1996b (Geomorphology)
• Cadol et al., 2011 (River Res Applic.)
• Dean and Schmidt, 2011 (Geomorphology)
• Scott et al., 2018 (Ecohydrology)
Channel incision• Simon and Rinaldi, 2006 (Geomorphology)
• Jaeger and Wohl, 2011 (Water Resour. Res.)Scott et al., 2018 (Ecohydrology)
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Control methods
https://www.nps.gov/glca/learn/nature/tamarisk-leaf-beetle.htm
USGS Russian Olive and Saltcedar Assessment
Mechanical (Whole Plant), Cut-Stump, Chemical, Biological,
Grazing, Fire, Flooding.
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MC, CSC, CC, BC, GC, FC, FlC
Removal of invasive vegetation: What happens next?
“Long-term monitoring and follow-up treatment are necessary”– USGS Saltcedar and Russian Olive Control Demonstration Act Science Assessment
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9
Rev
eget
atio
n
–
+
–
+
+
+
Flow Threshold Surface+ +
Time
Higher flow threshold
Drivers of post-removal channel change
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Remnant of
right bank
Flow
Bank toe
Vertical
eroded bank
Rio Puerco, photo: J. Friedman
Is there a flood?
How large was the flood?
How long after?
Aerial images of channel widening within the sprayed reach at Rio Puerco
Average
channel width
= 15.7 m
Average
channel width
= 35.7 m
October 1996
NAPP
photograph
Nov. 2006
satellite image
(DigitalGlobe)
content: J. Friedman
Native
vegetation loss
What we are seeing at
Canyon de Chelly NM…
Removal of riparian vegetation: What happens next?
Channel Widening
Bank
Slumping
Incision
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i) Literature Review
Site Name
Contributin
g Drainage
Area (km2)
Primary
Invasive
Vegetation Type
Removal
Control
Method
Amount of
Vegetation
Controlled
Control
Method
Timing
Post-removal
Channel
Response
Canyon de Chelly 1,500 RO, tamarisk MC, CSCFour 1.1-km
reaches2005 I, W
Rio Puerco 4,000 Tamarisk CC 12-km reach 2003 W
Escalante 5,200 RO CSC 50-km reach 2000-2018 ?
Rio Grande 471,400Tamarisk, Giant
cane, RO (NM) BC,FC, CC
150-km reach
(NM)? ?
Dolores 11,800 Tamarisk BC,CSC 280-km 2009 ?
Gila 150,700 Tamarisk FC,BC 25 acres 2015? ?
Verde 17,100
Tamarisk, RO,
Giant cane, Tree
of heaven
? ? 2012 ?
Colorado 637,100 Tamarisk, RO CSC,CC, BC ? ? ?
*W=widening, N=narrowing, I=incising
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What are the fundamental controls that govern the suite of probable channel responses following invasive vegetation removal?
How do different removal methods compare in terms of resulting stream morphologic changes?
Does mechanically removing the whole plant lead to the greatest channel morphologic response?
ii) Ongoing monitoring
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CACH XS and UAS Survey SitesWhole plant removal, cut-stump, and control areas at each site.
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CACH Aerial Imagery
Follow-up to Cadol et al., 2011 (River Res. Applic.)
Sources of imagery:
Google Earth, NAIP, NPS
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LWH Whole Plant – Channel Planform Delineations17
-5
-4.5
-4
-3.5
-3
-2.5
-2
-1.5
-1
-0.5
0
0102030405060708090100
Control
Cut Stump
Whole Plant
CACH – LWH XS – July 2019
Station (m)
Rel
ativ
e E
leva
tio
n (
m)
WP Previous active channel
0 10 20 30 40 50 60 70 80 90 100
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CACH – SPR – Nov 201919
10050Meters
1.77 km
1.8 km
1.83 km
iii) Geomorphic-Vegetation Interactions
Building on Dave Dean’s research• Dean and Schmidt, 2011
• Dean et al, 2011
• Dean and Schmidt, 2013Dean and Schmidt, 2011 (Geomorphology)
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1945 2008
Which type of vegetation imparts the greatest fluid drag, promoting deposition and channel narrowing?
Big Bend National Park (BIBE)
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Inform future vegetation management to:
Increase sediment conveyance
Limit channel narrowing
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Giant cane (Arundo Donax)
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“Seepwillow” (Baccharis salicifolia) Common Reed (Phragmites australis)
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Desert Willow
(Chilopsis linearis)
Summary
Understanding post-removal channel morphologic response is valuable to future river restoration.
A database of removal projects will be created to help interpret future channel response associated with invasive species removal. [email protected]
Future work in CACH will link flow characteristics to channel response, analyzing differences in control methods used on Elaeagnus angustifolia L. (Russian olive).
Future work in BIBE to investigate vegetation characteristics to flow and sediment transport dynamics among abundant plant types in Boquillas Canyon.
• Also, how has giant cane removal efforts affected channel morphology?
AcknowledgementsSara Rathburn
Colin Barry
Chris Holmquist-Johnson
Jonathan Friedman
Greg Auble
Lindsay Reynolds
Kris Jaeger
David Dean
Jeff Renfrow
Kevin Urbanczyk
Lee and Patty Gelatt
Mike Scott
Keith Lyons
Derek Shook
Juli Scamardo
Danny White
John Kemper
Travis Michel
Tony, Lily, Jake, and Ben
